This invention relates generally to open-end wrenches and specifically to such a wrench including a wrenching head with driving surfaces having serrated regions thereon.
A typical open-end wrench consists of an elongated handle and a wrenching head on either or both ends, the head including two jaws each with smooth planar driving surfaces that engage opposite sides of a polygonal fastener.
A disadvantage of such a wrench is the inadequate gripping force between the driving surfaces and the fastener. As a result, the wrench has a tendency to slip off the fastener when torque is applied thereto. That could be dangerous. Also, it increases stress in the fastener, tends to deform and spread the wrench jaws, and rounds and/or crushes the fastener corners.